What PLCP preamble type does the IEEE 802.11 standard, Clause 17 (OFDM) specify?

What PLCP preamble type does the IEEE 802.11 standard, Clause 17 (OFDM) specify?

A.
Fixed 56-bit preamble

B.
Fixed 12-symbol preamble

C.
Long 128-bit preamble

D.
Long 12-octet preamble

E.
Short 72-bit preamble

F.
Long 12-symbol preamble